Author: A. ÖdblomPublisher:
ISBN:
Category : Plasma (Ionized gases)
Languages : en
Pages : 19
Book Description
Sawteeth-induced Impurity Transport in Tokamak Plasmas
Author: A. ÖdblomPublisher:
ISBN:
Category : Plasma (Ionized gases)
Languages : en
Pages : 19
Book Description
Sawteeth-induced Transport in Tokamak Plasmas
Author: Anders ÖdblomPublisher:
ISBN: 9789171971647
Category :
Languages : en
Pages : 23
Book Description
Sawteeth and Other Transport Phenomena Induced by ExB-drifts in Tokamaks
Author: Andreas OedblomPublisher:
ISBN: 9789171975959
Category :
Languages : en
Pages : 9
Book Description
Impurity Transport in Tokamak Plasmas
Author: Peter DonnelPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Impurity transport is an issue of utmost importance for tokamaks. Indeed high-Z materials are only partially ionized in the plasma core, so that they can lead to prohibitive radiative losses even at low concentrations, and impact dramatically plasma performance and stability. On-axis accumulation of tungsten has been widely observed in tokamaks.While the very core impurity peaking is generally attributed to neoclassical effects, turbulent transport could well dominate in the gradient region at ITER relevant collisionality. Up to recently, first principles simulations of corresponding fluxes were performed with different dedicated codes, implicitly assuming that both transport channels are separable and therefore additive. The validity of this assumption is questionned. Simulations obtained with the gyrokinetic code GYSELA have shown clear evidences of a neoclassical-turbulence synergy for impurity transport and allowed the identification of a mechanism that underly this synergy.An analytical work allows to compute the level and the structure of the axisymmetric part of the electric potential knowing the turbulence intensity. Two mechanisms are found for the generation of poloidal asymmetries of the electric potential: flow compressibility and the ballooning of the turbulence. A new prediction for the neoclassical impurity flux in presence of large poloidal asymmetries and pressure anisotropies has been derived. A fair agreement has been found between the new theoretical prediction for neoclassical impurity flux and the results of a GYSELA simulation displaying large poloidal asymmetries and pressure anisotropies induced by the presence of turbulence.
Energy Research Abstracts
Author: Numerical Treatment of the Problem of Impurity Transport in Tokamak Plasma
Author: F. SpineanuImpurity Transport in a Quiescent Tokamak Plasma
Author: Samuel Alan CohenTransport Induced by Ion-impurity Friction in Strongly Rotating, Collisional Tokamak Plasma
Author: Chi-Tien HsuImpurity Transport Studies in Tokamak Edge Plasmas Using Visibe Imaging
Author: Sanjay GangadharaPublisher:
ISBN:
Category :
Languages : en
Pages : 6
Book Description
Understanding impurity transport in the scrape-off layer (SOL) of tokamak plasmas is a necessary piece of developing the physics basis for designing next-generation reactors. A system for inferring impurity transport parallel and perpendicular to local magnetic field lines has been developed on Alcator C-Mod using gas-injection "plumes". In this system, impurity gas is injected at a fixed position in the SOL via a reciprocating fast-scanning probe, and the resulting emission is imaged. In this paper visible light emission patterns from C+1 and C+2 ions are presented.
Some Effects of MHD Activity on Impurity Transport in the PBX Tokamak
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The effects of MHD activity on intrinsic impurity transport are studied in ohmic discharges of the Princeton Beta Experiment (PBX) by measuring of the Z/sub eff/ profile from visible bremsstrahlung radiation and the spectral line intensities from ultraviolet spectroscopy. A diffusive/convective transport model, including an internal disruption model, is used to simulate the data. The Z/sub eff/ profile with no MHD activity is fitted with a strong inward convection, characterized by a peaking parameter c/sub v/ (= -a2v/2rD) = 11 (3.5, +4.5). At the onset of MHD activity (a large m = 1 n = 1 oscillation followed by sawteeth), this strongly peaked profile is flattened and subsequently reaches a new quasi-equilibrium shape. This profile is characterized by reduced convection (c/sub v/ = 3.6 ( -1.1, +1.6), D = 1.4 ( -0.7, +5.6) x 104 cm2/s), in addition to the particle redistribution which accompanies the sawtooth internal disruptions. 10 figs.